A bustling city is sprouting on five acres here, carved out of a vast almond grove. Tanker trucks and heavy equipment come and go, a row of office trailers runs the length of the site and an imposing 150-foot drilling rig illuminated by football-field-like lights rises over the trees.

The headwaters of the Potomac River rise amid the hills and hollows of George Washington National Forest in Virginia. Small creeks dart past oak, white pine and hickory, become streams that nourish farmland and towns, and create a river that courses through two states and the nation's capital.

For years, Europe has tried to set the global standard for climate-change regulation, creating tough rules on emissions, mandating more use of renewable energy sources and arguably sacrificing some economic growth in the name of saving the planet.

Water samples collected at Colorado sites where hydraulic fracturing was used to extract natural gas show the presence of chemicals that have been linked to infertility, birth defects and cancer, scientists reported Monday.